Many automotive fuel tanks are flat in shape and, as a result, movement of the vehicle may cause the fuel pump pickup to become uncovered. When this happens, the engine's lift pump may draw air into the fuel system, with the result that the engine may stall or run roughly. In an effort to prevent such stalling caused by the ingestion of air in the fuel system, vehicle designers have used a reservoir about the fuel pump pickup. Such a reservoir is disclosed in U.S. Pat. No. 4,899,784 to Woodgate et al.
If a reservoir is used for the purpose of helping to maintain fuel about a pickup, keeping the reservoir filled may be a problem. The '784 patent cited above uses a return line from the engine to induce flow into the reservoir. This system suffers from a drawback which is shared by all such reservoirs insofar as the reservoir can fill only to the extend that fuel is actually running through the system. In other words, if the engine is either starved for fuel or air bound, the filling mechanism will not help.
It is an advantage of the present advantage that a fuel pickup and reservoir according to this invention will allow the engine to keep running even at very low levels of fuel in the fuel tank and, of equal importance, it will allow the engine's fuel system to purge itself of air if the engine is operated until the fuel pickup is uncovered such that air has been ingested into the system.
According to the present invention, a fuel reservoir system for an internal combustion engine comprises a canister (22) having a storage volume (24) for holding fuel, at least one fuel supply line (26) extending from the canister to the engine, an entrance pipe (28) for conducting raw fuel into the canister, and an exit pipe (32) connected with a fuel supply line for conducting fuel from the canister to the fuel supply line. The exit pipe comprises a draft tube (34) extending into the lower part of the storage volume, a purge passage (36) communicating the upper portion of the draft tube with the storage volume, and a flow restrictor (38,40) mounted in the draft tube upstream of the purge passage.